The possible association of herpes simplex type 1, type 2, and Epstein-Barr (EB) virus with specific cell chromosomes will be studied. The techniques of interspecies somatic cell hybridization will be used. Transformed cells of one species, carrying viral thymidine kinase, will be hybridized to thymidine kinase deficient cells of a different species. The hybrids will be propagated in selective medium. Following chromosome loss, the cells will be examined to see if herpes simplex or EB viral genomes are associated with chromosomes, and if so, which chromosomes.